Wondering if anyone has thought to use a 12v mini air compressor ,which some will go to 300 psi, and a receiver tank of 10 gal. or more to run the air system .Just hook up a regulator and let 2 or 3 psi bleed out for, who know how long it would take the have pressure switch kick it back on and bring up the pressure back up and start the cycle all over again. Wounder if it would be cheaper or better off the grid system.
One would need to check how much juice the compressor draws during the time it takes to bring the tank back up to pressure (then compare to how much juice is needed to run the regular air pump continuously) and since volume over pressure is usually needed for most aquaponic air systems, I'm not sure if the compressor is really the best way to go. Also, you have to make sure it is an oilless compressor or you have to set it up with an oil trap so that you can't get oil going down the air lines into your air stones and into your fish water.
Now if this is a viable option, I would think that a larger storage tank might be even better. I've heard of people using air stored in air compressor tanks for use during power out or transport but I don't know how much it delivers or lasts. Seems to me that it would only run a very short time before too much pressure was gone but I haven't tried it myself.